Ginkgo (Ginkgo biloba)

Ginkgo is used by patients with cognitive disorders, peripheral vascular disease, age-related macular degeneration, vertigo, tinnitus, erectile dysfunction, and altitude sickness. Ginkgo may stabilize or improve cognitive performance in patients with Alzheimer's disease and multi-infarct dementia^{[46] [47]} but not in healthy patients.^[48]

The compounds believed to be responsible for ginkgo's pharmacologic effects are the terpenoids (i.e., bilobalide and ginkgolides A, B, C and J) and flavonoids (i.e., kaempferol, quercetin, and isorhamnetin derivatives). These compounds alter vasoregulation,^[49] act as antioxidants,^[50] modulate neurotransmitter and receptor activity,^{[51] [52]} and inhibit platelet-activating factor (PAF). ^[53] Of these effects, the inhibition of PAF is the most worrisome given the potential for inhibition of platelet function. Clinical trials enrolling a small number of patients have not demonstrated bleeding complications, but one case of postoperative bleeding after laparoscopic cholecystectomy,^[54] four reported cases of spontaneous intracranial bleeding,^{[55] [56] [57] [58]} and one case of spontaneous hyphema^[59] have been attributed to ginkgo use. Ginkgo also has been associated with seizures.^[60]

Elimination half-lives of bilobalide and ginkgolides A and B after oral administration are 4.5, 10.6, and 3.2 hours, respectively.^[61] Based on the pharmacokinetic data and the risk of bleeding, ginkgo should be discontinued at least 36 hours before surgery.